﻿using System;
using System.Web;
using System.Drawing;
using System.Security.Cryptography;

namespace DotNet.Utilities
{
	/// <summary>
	/// 验证码类
	/// </summary>
	public class Rand
	{
		#region 生成随机数字
		/// <summary>
		/// 生成随机数字
		/// </summary>
		/// <param name="length">生成长度</param>
		public static string Number(int Length)
		{
			return Number(Length, false);
		}

		/// <summary>
		/// 生成随机数字
		/// </summary>
		/// <param name="Length">生成长度</param>
		/// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
		public static string Number(int Length, bool Sleep)
		{
			if (Sleep) System.Threading.Thread.Sleep(3);
			string result = "";
			System.Random random = new Random();
			for (int i = 0; i < Length; i++)
			{
				result += random.Next(10).ToString();
			}
			return result;
		}
		#endregion

		#region 生成随机字母与数字
		/// <summary>
		/// 生成随机字母与数字
		/// </summary>
		/// <param name="IntStr">生成长度</param>
		public static string Str(int Length)
		{
			return Str(Length, false);
		}

		/// <summary>
		/// 生成随机字母与数字
		/// </summary>
		/// <param name="Length">生成长度</param>
		/// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
		public static string Str(int Length, bool Sleep)
		{
			if (Sleep) System.Threading.Thread.Sleep(3);
			char[] Pattern = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
			string result = "";
			int n = Pattern.Length;
			System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));
			for (int i = 0; i < Length; i++)
			{
				int rnd = random.Next(0, n);
				result += Pattern[rnd];
			}
			return result;
		}
		#endregion

		#region 生成随机纯字母随机数
		/// <summary>
		/// 生成随机纯字母随机数
		/// </summary>
		/// <param name="IntStr">生成长度</param>
		public static string Str_char(int Length)
		{
			return Str_char(Length, false);
		}

		/// <summary>
		/// 生成随机纯字母随机数
		/// </summary>
		/// <param name="Length">生成长度</param>
		/// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
		public static string Str_char(int Length, bool Sleep)
		{
			if (Sleep) System.Threading.Thread.Sleep(3);
			char[] Pattern = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
			string result = "";
			int n = Pattern.Length;
			System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));
			for (int i = 0; i < Length; i++)
			{
				int rnd = random.Next(0, n);
				result += Pattern[rnd];
			}
			return result;
		}
		#endregion
	}

	/// <summary>
	/// 验证图片类
	/// </summary>
	public class YZMHelper
	{
		#region 私有字段
		private string text;
		private Bitmap image;
		private int letterCount = 4;   //验证码位数
		private int letterWidth = 16;  //单个字体的宽度范围
		private int letterHeight = 20; //单个字体的高度范围
		private static byte[] randb = new byte[4];
		private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();
		private Font[] fonts = 
    {
       new Font(new FontFamily("Times New Roman"),10 +Next(1),System.Drawing.FontStyle.Regular),
       new Font(new FontFamily("Georgia"), 10 + Next(1),System.Drawing.FontStyle.Regular),
       new Font(new FontFamily("Arial"), 10 + Next(1),System.Drawing.FontStyle.Regular),
       new Font(new FontFamily("Comic Sans MS"), 10 + Next(1),System.Drawing.FontStyle.Regular)
    };
		#endregion

		#region 公有属性
		/// <summary>
		/// 验证码
		/// </summary>
		public string Text
		{
			get { return this.text; }
		}

		/// <summary>
		/// 验证码图片
		/// </summary>
		public Bitmap Image
		{
			get { return this.image; }
		}
		#endregion

		#region 构造函数
		public YZMHelper()
		{
			HttpContext.Current.Response.Expires = 0;
			HttpContext.Current.Response.Buffer = true;
			HttpContext.Current.Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);
			HttpContext.Current.Response.AddHeader("pragma", "no-cache");
			HttpContext.Current.Response.CacheControl = "no-cache";
			this.text = Rand.Number(4);
			CreateImage();
		}
		#endregion

		#region 私有方法
		/// <summary>
		/// 获得下一个随机数
		/// </summary>
		/// <param name="max">最大值</param>
		private static int Next(int max)
		{
			rand.GetBytes(randb);
			int value = BitConverter.ToInt32(randb, 0);
			value = value % (max + 1);
			if (value < 0) value = -value;
			return value;
		}

		/// <summary>
		/// 获得下一个随机数
		/// </summary>
		/// <param name="min">最小值</param>
		/// <param name="max">最大值</param>
		private static int Next(int min, int max)
		{
			int value = Next(max - min) + min;
			return value;
		}
		#endregion

		#region 公共方法
		/// <summary>
		/// 绘制验证码
		/// </summary>
		public void CreateImage()
		{
			int int_ImageWidth = this.text.Length * letterWidth;
			Bitmap image = new Bitmap(int_ImageWidth, letterHeight);
			Graphics g = Graphics.FromImage(image);
			g.Clear(Color.White);
			for (int i = 0; i < 2; i++)
			{
				int x1 = Next(image.Width - 1);
				int x2 = Next(image.Width - 1);
				int y1 = Next(image.Height - 1);
				int y2 = Next(image.Height - 1);
				g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
			}
			int _x = -12, _y = 0;
			for (int int_index = 0; int_index < this.text.Length; int_index++)
			{
				_x += Next(12, 16);
				_y = Next(-2, 2);
				string str_char = this.text.Substring(int_index, 1);
				str_char = Next(1) == 1 ? str_char.ToLower() : str_char.ToUpper();
				Brush newBrush = new SolidBrush(GetRandomColor());
				Point thePos = new Point(_x, _y);
				g.DrawString(str_char, fonts[Next(fonts.Length - 1)], newBrush, thePos);
			}
			for (int i = 0; i < 10; i++)
			{
				int x = Next(image.Width - 1);
				int y = Next(image.Height - 1);
				image.SetPixel(x, y, Color.FromArgb(Next(0, 255), Next(0, 255), Next(0, 255)));
			}
			image = TwistImage(image, true, Next(1, 3), Next(4, 6));
			g.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, (letterHeight - 1));
			this.image = image;
		}

		/// <summary>
		/// 字体随机颜色
		/// </summary>
		public Color GetRandomColor()
		{
			Random RandomNum_First = new Random((int)DateTime.Now.Ticks);
			System.Threading.Thread.Sleep(RandomNum_First.Next(50));
			Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);
			int int_Red = RandomNum_First.Next(180);
			int int_Green = RandomNum_Sencond.Next(180);
			int int_Blue = (int_Red + int_Green > 300) ? 0 : 400 - int_Red - int_Green;
			int_Blue = (int_Blue > 255) ? 255 : int_Blue;
			return Color.FromArgb(int_Red, int_Green, int_Blue);
		}

		/// <summary>
		/// 正弦曲线Wave扭曲图片
		/// </summary>
		/// <param name="srcBmp">图片路径</param>
		/// <param name="bXDir">如果扭曲则选择为True</param>
		/// <param name="nMultValue">波形的幅度倍数，越大扭曲的程度越高,一般为3</param>
		/// <param name="dPhase">波形的起始相位,取值区间[0-2*PI)</param>
		public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
		{
			double PI = 6.283185307179586476925286766559;
			Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
			Graphics graph = Graphics.FromImage(destBmp);
			graph.FillRectangle(new SolidBrush(Color.White), 0, 0, destBmp.Width, destBmp.Height);
			graph.Dispose();
			double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;
			for (int i = 0; i < destBmp.Width; i++)
			{
				for (int j = 0; j < destBmp.Height; j++)
				{
					double dx = 0;
					dx = bXDir ? (PI * (double)j) / dBaseAxisLen : (PI * (double)i) / dBaseAxisLen;
					dx += dPhase;
					double dy = Math.Sin(dx);
					int nOldX = 0, nOldY = 0;
					nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
					nOldY = bXDir ? j : j + (int)(dy * dMultValue);

					Color color = srcBmp.GetPixel(i, j);
					if (nOldX >= 0 && nOldX < destBmp.Width
					 && nOldY >= 0 && nOldY < destBmp.Height)
					{
						destBmp.SetPixel(nOldX, nOldY, color);
					}
				}
			}
			srcBmp.Dispose();
			return destBmp;
		}
		#endregion
	}
}